A substantial saving of material cost and weight is obtained in an induction motor by a rotor including two sets of differently punched laminations. The laminations in one of the two groups each weigh less than 95% of the laminations in the other one of the two groups. Such laminations can be automatically produced on a computer-controlled die press by providing a separate punch pattern that is capable of being programmed for selected laminations. The lighter laminations can be used to counterbalance a crank without requiring additional counterbalancing weight to be added outside the motor.